Can a microtopping be stained or polished?

Yes. A microtopping takes color mixed in, acid or water-based stain, and saw-cut lines. A self-leveling topping goes further. Once it cures, it acts like a real slab, so it grinds and polishes like one. That's what our polished overlay is: about 3/8 inch of new cement poured over a rough slab, then ground, honed, and polished to a high gloss.

Do I need a bonding agent or primer?

Most overlay systems call for a primer or bond coat matched to the topping by its maker. It's an acrylic or epoxy slurry that ties the topping to the slab. Timing it is its own small craft. Go in before the primer gets tacky, or wait until it has dried past that point, and either way you lose the bond. Skipping the primer to save an hour is how a topping that looked fine on install day starts sounding hollow a year later.

Concrete overlay FAQ: types, bonding, and cost

Q: What is a concrete overlay?

A concrete overlay is a thin cement-based or polymer-modified topping bonded onto the slab you already have. It renews the surface without a tear-out. It runs from about 1/16 inch thick for a microtopping up to roughly 1 inch for a self-leveling pour. Think second skin, not a coat of paint. It only holds if it grips the concrete under it, and when the prep is wrong, it lifts.

Q: How thick can a concrete overlay be?

Most overlays run from 1/16 inch for a microtopping up to about 1 inch for a self-leveling pour. Polymer-modified resurfacers feather out to a hair and build to about 1/2 inch, and a stamped overlay runs 1/4 to 3/4 inch. Go past roughly 2 inches and it's not a decorative overlay anymore. It's a bonded topping slab under ACI 546 repair guidance, and that brings its own steel, joint layout, and engineering review.

Q: What surface profile does an overlay need to bond?

Most overlays need the surface opened up to CSP 2 to 4. That's a rating on the ICRI 310.2 Concrete Surface Profile scale, and we get there by shot blasting or diamond grinding. Acid alone won't do it for a real bond. Think of roughing up a surface before you glue it, not just wiping it with a rag. The slab needs tooth, not only clean. A profile number alone doesn't prove the slab is ready, so we check that it soaks up water too: a drop on the prepped slab should darken it and sink in, not bead up. The slab also has to be free of oil, sealers, curing compounds, and the weak, dusty top layer called laitance before any primer goes down.

Q: How do you test that an overlay bonded correctly?

A pull-off test per ASTM C1583 checks the bond after the overlay cures. It pulls straight up on the topping, and a sound job holds past 200 psi. On a questionable slab, a crew can also run an ASTM D7234 pull-off test before committing to the full pour. Short of a lab test, there's a plain version anybody can run: walk the floor. A hollow sound underfoot means the bond didn't take.

Q: Does a concrete slab need to be dry before overlaying?

Yes. Moisture is the quiet overlay killer. A slab pushing up vapor lifts the topping from below no matter how good the primer is, and you won't see it coming until the floor sounds hollow. An ASTM F1869 calcium chloride test should read under 3 lbs per 1,000 square feet over 24 hours. An ASTM F2170 probe, which reads the humidity inside the slab, should read under 75 percent. Slabs below grade or with no vapor barrier are the usual problems.

Q: Can you grind out an old tile pattern and the thinset left behind?

Sometimes, and often the smarter move is to cover it. Grinding takes off thinset ridges and glue. But tile leaves a grid of harder and softer concrete under it, and that grid can still ghost through a thin finish long after the glue is gone. If the ghosting would bother you, a self-leveling or polymer-modified overlay buries the grid under one even new surface instead of chasing it with a grinder. Ask for a test spot ground in a corner first, because the bare slab under old tile rarely looks the way people picture it.

Q: When should I resurface concrete instead of replacing it?

Resurface when the slab is sound and the damage is only skin deep: a worn top, stains, hairline shrinkage cracks, or light spalling (small chips and flakes). An overlay renews that surface for $4.48 to $10.44 a square foot and skips the tear-out. Replace when the slab is moving, heaving, settling, or fed by groundwater. Put a topping on concrete that's still shifting and you've paid to watch the same problem happen twice.

Last updated: October 28, 2026

This concrete overlay FAQ puts a number on every answer. A concrete overlay renews a worn slab for $4.48 to $10.44 a square foot installed. A tear-out and re-pour starts at $7.85 and goes up from there. These are the questions our crews hear on nearly every resurfacing call: how thick the topping goes, what makes it bond, how long it lasts, and when the slab says replace instead of resurface.

Overlay types and thickness

Thickness picks the system, and the system picks the finish.

What is a concrete overlay?

A concrete overlay is a thin topping, cement-based or polymer-modified, bonded to the slab you already have. It renews the surface with no demolition. Some people call it a cement overlay or a bonded overlay. It runs from 1/16 inch for a microtopping up to about 1 inch for a self-leveling pour. The bond is most of the game. A topping that doesn’t grip the old slab sheets off within a season, no matter how good the product was. The full menu of systems is on our concrete overlays service page.

What are the main types of concrete overlay?

Five systems cover almost every job. A microtopping is a colored skim coat around 1/16 inch, troweled on in two or three passes. A self-leveling overlay flows out at 1/4 to 1 inch and fixes a slab that’s out of flat. The other three handle texture and outdoor wear:

Polymer-modified resurfacer: feathers out to a hair, builds to 1/2 inch, and suits worn outdoor concrete.
Spray-down or knockdown: 1/8 to 1/4 inch of texture for pool decks and patios.
Stampable overlay: 1/4 to 3/4 inch, pressed with a stone, brick, or wood-plank pattern.

Match the system to the slab and the finish. Not to whatever’s already on the truck.

How thick can a concrete overlay be?

Thickness follows the system. A microtopping holds at 1/16 inch. Self-leveling runs 1/4 to 1 inch. Polymer-modified resurfacers feather out and build to 1/2 inch, and a stamped overlay is 1/4 to 3/4 inch thick. Go past the rated depth and you’ve invited shrinkage cracks. Above roughly 2 inches you’ve left overlay country. That’s a bonded topping slab under ACI 546 repair guidance, with its own steel plan, joint layout, and engineering review before a single bag gets mixed. The concrete overlay guide walks through the thickness math.

Surface prep and bonding

Prep is the step a contractor cuts to save a day. It’s also the step behind nearly every overlay failure we get called out to look at, and the slab never lies about which corner got cut.

What surface profile does an overlay need to bond?

An overlay won’t glue itself to a smooth slab. It needs tooth, a roughed-up surface it can grab. ICRI Guideline 310.2 rates that roughness as a Concrete Surface Profile, from CSP 1 (smooth) up to CSP 9 (very rough). Most cement-based overlays call for CSP 2 to 4, opened up by diamond grinding or shot blasting. A slick steel-troweled floor reads as CSP 1. It’s the most common cause of an overlay peeling loose (delamination) that we see in the field. Acid etching alone won’t fix it.

A profile number isn’t the whole test, either. The grind is there to open the pores so the primer can soak in. So if a drop of water beads up on the ground surface, the pores are still closed, no matter what the profile reads.

Does a concrete slab need to be dry before overlaying?

Yes, and moisture is the quiet killer here. A slab pushing up vapor blows an overlay off from below, no matter how good the primer is. So we look over every slab first. When it raises a flag, we add the tests to the scope before any topping goes down. The flags are a slab below grade, no vapor barrier, an old coating that failed, or stains you can see. The tests are an ASTM F1869 calcium chloride test, which should read under 3 lbs per 1,000 square feet over 24 hours, and an ASTM F2170 probe that reads the humidity inside the slab. If you want the test on a slab with no flags, ask and we’ll run it. The reading tells us if a moisture barrier coat goes down first.

How do you test that an overlay bonded correctly?

After the topping cures, an ASTM C1583 pull-off test checks the bond. It pulls straight up on the topping, and a sound job holds past 200 psi. On a questionable slab, a crew can run that same test before the full pour to make sure the prep took. The plain read is simpler than the lab work. A floor that sounds hollow underfoot a few months in didn’t bond, and no amount of sealer saves it.

Can you grind out an old tile pattern and the thinset left behind?

Yes, the old glue comes up. A grinder pulls thinset ridges and leftover glue off a slab. The pattern is the part people don’t expect. Tile and its mortar bed make the concrete under them cure unevenly. The slab ends up a checkerboard of harder squares and softer grout lines, and that shows in how it takes a grind, a hardener, or a stain. Grind it flat and clean, and the grid can still read through as ghosting when the light hits it right.

So that’s the real choice. If you want the bare slab and can live with some pattern showing, grinding is the shorter path. If you want the ghosting gone, cover it. A self-leveling or polymer-modified overlay lays one even new surface across the whole floor. Then the grid stops mattering, because the finish isn’t reading the old concrete anymore. Cutback adhesive and mastic, the black tile glues, push the same way. Getting them all off is slow work, and an overlay only needs what’s left to be sound and stable.

Either way, ask for a test spot first. A few square feet ground in a corner shows what your slab really looks like under the tile. That’s usually the fastest way to settle it without guessing.

Resurface versus replace decisions

The slab makes this call, not the price tag. Read the slab first, then pick the path.

When should I resurface concrete instead of replacing it?

Resurface a healthy slab. Replace a failing one. Say the concrete is solid and the damage is only skin deep: a worn top, stains, hairline cracks, or light spalling (small chips and flakes). Then a bonded overlay renews it for $4.48 to $10.44 a square foot and skips the demolition. But if the slab is moving, heaving, settling, or fed by groundwater, the overlay fails right along with it. Then that cheap topping just adds to the bill for the tear-out you needed anyway. Our overlay vs replacement guide lays out the full decision.

Can you overlay concrete that has cracks?

It depends on the crack. Hairline shrinkage cracks that sit still get routed out, filled, and overlaid without trouble. Two kinds don’t. Working cracks open and close with the temperature. Structural cracks have one side sitting higher than the other. Both show straight through any topping within a season or two. ACI 224.1R sorts cracks by cause. The short version: an active crack is a movement problem, not a surface problem, and a topping can’t bridge a slab that keeps moving under it.

What slab problems rule out an overlay?

Four things push a job from resurface to replace:

Working or structural cracks
Heaving or settling, where the slab isn’t flat anymore
A failed or unstable base under the slab
A slab below grade with active moisture

Any one of those means the base itself is the problem, so a topping just moves the failure up to the new surface. When that’s what we find, we say so. Our concrete repair and resurfacing work covers the patch-and-overlay path when the slab can be saved.

Cost and value

How much does a concrete overlay cost per square foot?

An installed concrete overlay costs $4.48 to $10.44 a square foot with us. Each system has its own starting price.

Overlay	Starts at, per sq ft	What you get
Basic overlay	$4.36	A thin, colored cement skin about the thickness of a nickel. Primed, troweled, and sealed.
Patterned overlay	$6.14	The look of tile, stone, brick, or wood plank. Textured, stained, and sealed.
Polished overlay	$9.86	About 3/8 inch poured over a rough slab, then ground and polished to a high gloss.

The range above includes setup. A single rate can sit a little under it. Stain, saw-cut lines, or a stamped pattern push a job up from those starting points. The topping itself isn’t what drives the spread. The prep and the decorative work are. The diamond grinding and shot blasting are what keep the overlay on the floor for 15 years instead of two.

Is a concrete overlay cheaper than replacement?

Almost always. An overlay over a sound slab runs $4.48 to $10.44 a square foot installed. A full tear-out and new slab starts at $7.85 a square foot once demo, haul-off, base prep, and the new pour are counted. The top of the overlay range is the decorative work, so weigh it against a new slab with the same look, not a plain gray one. The savings come from skipping all that demo and pouring. But the math only favors resurfacing when the slab qualifies. An overlay over a moving slab lasts one season, and then you replace the slab anyway. Match the spend to the slab. Get a price in about 2 minutes and we’ll tell you which path fits.

Durability and finishes

A bonded overlay lasts about as long as the slab under it, and the finish you pick rarely cuts that short.

How long does a concrete overlay last?

A well-bonded indoor overlay over a sound slab lasts 10 to 20 years. Sealed and cared for on schedule, it often lasts the full life of the floor. Outdoor overlays in freeze-thaw country run 8 to 15 years before the sealer and surface want a refresh. The bond decides it. The slab’s condition and the prep that opened it to CSP 2 to 4 matter far more than the topping product. And a self-leveling overlay that gets ground and polished after it cures holds its guard coat for 3 to 5 years between refreshes.

What finishes can a concrete overlay take?

The range of looks is wide. Microtoppings take color mixed in, acid or water-based stain, and saw-cut lines. Stampable overlays press stone, brick, or wood-plank texture into a 1/4 to 3/4 inch layer over a tired patio. A RESA resin topcoat over a cement-based overlay adds a layer that stands up to chemicals and wear. And a Slab Boss densified-polish finish turns a self-leveling overlay into a hard, shiny floor. Match the finish to the room’s traffic first and the slab’s condition second.

Will an overlay hold up to vehicle traffic?

A polymer-modified or stampable overlay at the right thickness handles driveway and garage loads once it’s fully cured. Most polymer-modified systems can take foot traffic in 4 to 6 hours at 70 degrees, and cars at 48 to 72 hours. A microtopping at 1/16 inch is a decorative indoor finish. It isn’t rated for cars, and parking one on it is how a thin system fails early.

Maintenance

How do you maintain a sealed concrete overlay?

Upkeep stays light. A sealed microtopping wants a reseal every 2 to 4 years, depending on traffic. A self-leveling overlay cared for like a polished floor holds its guard coat a good 3 to 5 years between visits and needs almost nothing in between. Day to day, dust mop for grit and damp mop with a neutral pH cleaner. Skip the bleach. Acidic cleaners and vinegar eat at the surface over months of use. That’s why we hand over a care schedule with each job. It spells out when the next reseal comes due.

How long does an overlay installation take?

Most home jobs of 500 to 1,500 square feet finish in one to two days. Day one is surface prep and putting the overlay down. Day two is curing and sealing. When you can walk or drive on it depends on the system: light foot traffic around 24 hours, and cars at 48 to 72 hours. The quote carries a firm timeline.

Can you stay open while the work happens? Usually, yes. The crew splits the floor into sections and works one at a time, so the rest of the building keeps running. The cure time sets how big each section can be. The topping goes down, that area closes for its 24 hours of foot-traffic cure, and then it opens back up before the next section starts. Kitchens, store floors, and warehouses all get done this way. Evening or weekend hours shrink the overlap even more.

Staying open isn’t the same as staying normal, though. The section being ground is loud and throws dust, so it gets tented off and vacuumed. The section curing is off limits to everybody, staff included, because foot traffic on a fresh surface is exactly how a section gets lost. Plan on giving up one zone at a time. You’ll walk a longer route through your own building for a couple of days. And agree on the zone order in a walk-through before anybody starts.

If the floor can close instead, take that option. One continuous pour beats sections on both cost and finish, because every section seam is a spot where two pours meet. When closing isn’t realistic, sections work, and we build the schedule around your hours, not ours.

Getting started

How do I get a quote for a concrete overlay?

Use the online quote tool to get a price for your project in about 2 minutes, or send a few photos of your slab. We read the slab before we quote, because the slab decision comes before the surface decision every time. The quote spells out the system, the prep, and the price up front. And there’s no sales pitch to resurface a floor that ought to be replaced.

Not sure whether your slab takes an overlay?

Send a few photos of your slab. We’ll tell you straight whether a topping will hold or the base has to come out, and what each path costs. No pressure, no callback wait.

Get your price now